This invention relates to novel, easily crystallized prostanoic acid esters and to a process for their production.
Prostaglandins are known to be novel hormones having a wide activity spectrum. They are effective in small amounts as vasodilatory agents and bronchodilators, they affect fat metabolism and they are utilized as agents for initiating abortion and for inducing labor.
German Unexamined Laid-Open Applications DOS 2,155,546, 2,159,509 and 2,117,188 disclose prostaglandin esters showing a better effectiveness than the free acids. The essential disadvantage of these esters resides in that they are in most cases oily or difficult-to-crystallize compounds, so that they can be purified only under great difficulties. Moreover, complicated processes are required for their preparation. Thus, after converting the prostanoic acids into a tertiary amine salt, a mixed anhydride is first prepared, in DOS 2,155,546 with a pivaloyl halogenide, and in DOS 2,159,509 with an alkyl or phenyl sulfonyl halogenide, and this anhydride is then reacted with an alcohol to produce the prostaglandin ester.
It has now been found that by reacting prostanoic acids with certain halogen compounds as defined hereinafter, crystalline prostanoic acid esters having the same or superior activity compared to the corresponding free acid are obtained in good yields in a single stage.